Showing papers in "Geological Magazine in 1953"
TL;DR: The cross-bedding of the Lower Cretaceous Sands between Leighton Buzzard and Hunstanton has been studied in detail in this article, where new evidence which throws further light on the depositional environment and palaeogeography of these sediments is described.
Abstract: The cross-bedding of the Lower Cretaceous sands between Leighton Buzzard and Hunstanton has been studied. This paper describes new evidence which throws further light on the depositional environment and palaeogeography of these sediments.Both cross-bedding and grain size distribution were investigated in detail in the Woburn Sands (Aptian). These beds lie between Cambridge and Leighton Buzzard (Cameron, in Kirkaldy, 1939, p. 407), and are the youngest “;Lower Greensand” of East Anglia. Rather less attention has been paid to the pre-Barremian Sandringham Sands (Downham to Hunstanton). Unfortunately, the Carstone of Hunstanton shows no cross-bedding.
44 citations
TL;DR: In this article, it was shown that, chemically, a Fe 2 O 3 :Al 2 O O 3 ratio of about 0.40 is critical for the formation of chloritoid or staurolite, but if the value exceeds a figure somewhere between 0.47 and 0.55, a reddish-brown biotite appears instead.
Abstract: "In the pelitic rocks of this classical section it appears that, chemically, a Fe 2 O 3 :Al 2 O 3 ratio of about 0.40 is critical for the formation of chloritoid or staurolite. With this ratio both minerals are possible, but if the value exceeds a figure somewhere between 0.47 and 0.55 staurolite cannot form, a reddish-brown biotite appearing instead. Physically, a certain minimum temperature is necessary before staurolite can appear and below this chloritoid is the equilibrium phase."
33 citations
TL;DR: In this article, a number of observations of orientation of current-bedding in the Moine series of Inverness-shire, Wester Ross and Sutherland, in the north-western Highlands of Scotland were made.
Abstract: "This note records a number of observations of orientation of current-bedding in the Moine series of Inverness-shire, Wester Ross and Sutherland, in the north-western Highlands of Scotland. The foreset beds have been found to have a dominant dip towards the north, thus suggesting that the currents responsible for the transport of the material forming these beds flowed from the south."
33 citations
TL;DR: Describes Lepidostrobus zea n.sp.
Abstract: Describes Lepidostrobus zea n.sp. from Carboniferous deposits of Yorkshire, England, and Ayshire, Scotland, and discusses associated mega-and microspores.
31 citations
TL;DR: The results of gravity surveys over various exposed and buried acid intrusions are summarized in this paper, and sample density determinations are discussed, and it is found that acid intrusion considered are almost invariably associated with negative Bouguer anomalies, which are certainly often caused by direct density contrast between the less dense acid intrusive, and the denser country rock.
Abstract: The results of gravity surveys over various exposed and buried acid intrusions are summarized Some sample density determinations are discussed It is found that the acid intrusions considered are almost invariably associated with negative Bouguer anomalies, which are certainly often caused by direct density contrast between the less dense acid intrusive, and the denser country rock This has two immediate implications (1) Large negative Bouguer anomalies over “granites” may suggest magmatic origin (2) These gravity anomalies, supported by seismological and seismic evidence, and the petrological distribution of igneous rocks, lead to the postulation of a denser “metasedimentary” layer overlying the “granitic” layer The bearing of this on the mechanism of intrusion is briefly discussed
25 citations
TL;DR: In this article, the results between and near Newcastle and Durham are fully consistent with the conception of a horst, uplifted between the Ninety Fathom Dyke and the Butterknowle Fault.
Abstract: Gravity measurements in Durham and Northumberland in the region of the Alston Block are described, and their reduction as well as the accuracy of the results discussed. It is shown that the results between and near Newcastle and Durham are fully consistent with the conception of a horst, uplifted between the Ninety Fathom Dyke and the Butterknowle Fault. The observations along the valley of the East Allen, however, require an entirely different explanation. It is concluded that a closed area of negative anomalies occurs, centred near Wear Head. This is interpreted as due to a granite intrusion not yet exposed by denudation. The mineralization of the area is discussed and it is shown that it supports the foregoing interpretation.
22 citations
TL;DR: In this article, five breccias occur in the Carboniferous rocks of The Billefjorden area of West Spitsbergen and they are explained as due to collapse following solution in underlying strata.
Abstract: Five breccias occur in the Carboniferous rocks of The Billefjorden area of West Spitsbergen. Evidence poins to the origin of some of the breccia beds as due to collapse following solution in underlying strata; others are yet to be explained. It is certain, however, that none of the breccias originated under unstable depositional conditions.
22 citations
TL;DR: In this paper, the authors investigated the olivines in the picrite, picrodolerite, and crinanite of the Garbh Eilean sill.
Abstract: The investigation of the olivines in the picrite, picrodolerite, and crinanite of the Garbh Eilean sill is part of a research program on the geochemistry and petrology of the rocks of the Shiant isles, situated 20 miles off the west coast of Scotland. Optical and chemical work on specimens from a section of the sill, extending from sea level up to 395 feet, shows that the olivines in the upper picrodolerite and the crinanite are zoned, the range of zoning and the iron content increasing with height.
22 citations
TL;DR: In this paper, a negative Bouguer anomaly was found in the upper Weardale area, and the preferred explanation was a buried acid intrusion, and deductions growing out of this possibility are presented.
Abstract: Gravity measurements in northern England, west of Newcastle, have shown a negative Bouguer anomaly in the upper Weardale area. The preferred explanation is a buried acid intrusion, and deductions growing out of this possibility are presented.
21 citations
TL;DR: Petrofabric analyses of marble specimens from three widely separated localities in Mid-Strathspey and Strathavon are recorded in this paper, where the preferred orientation of [0001] in the constituent grains of calcite conforms to a B-tectonite pattern, the symmetry axis (B) of which coincides with the b axis of the megascopic fabric at each locality.
Abstract: Petrofabric analyses of marble specimens from three widely separated localities in Mid-Strathspey and Strathavon are recorded. Preferred orientation of [0001] in the constituent grains of calcite conforms to a B-tectonite pattern, the symmetry axis (B) of which coincides with the b axis of the megascopic fabric (lineation and fold axis) at each locality. Development of {011¯2} lamellae in calcite grains is attributed to late minor compression, the direction of which is more or less horizontal and trends between N.E.–S.W. and E.N.E.–W.S.W.
19 citations
TL;DR: The ultramafic rocks of Queensland show similarity in field relationships, tectonics, petrology, and chemistry with those of New South Wales and probably belong to one belt.
Abstract: The ultramafic rocks of Queensland show similarity in field relationships, tectonics, petrology, and chemistry with those of New South Wales and probably belong to one belt. They comprise three groups, namely, massive serpentinites, schistose serpentinites, and composite rocks, characterized by a schistose matrix with inclusions of the massive variety. It is suggested that two phases of ultramafic activity occurred along the fracture system where the rocks are found, possibly in both the middle Devonian and lower Carboniferous periods. The serpentinite breccias, formation of antigorite, and the problem of genesis are discussed.
TL;DR: The stage name Breconian was first used during the 18th International Geological Congress in London, but has never been explicitly defined as discussed by the authors, which signifies that part of the Old Red Sandstone between the Dittonian and Farlovian stages, and is particularly well developed in Breconshire, southern Wales.
Abstract: The stage name Breconian was first used during the 18th International Geological Congress in London, but has never been explicitly defined. It signifies that part of the Old Red Sandstone between the Dittonian and Farlovian stages, and is particularly well developed in Breconshire, southern Wales, the type area. It comprises the Senni beds and the Brownstones, together about 2,100 feet thick.
TL;DR: It appears that there are two forms of Monograptus dubius which have the same external appearance but differ in the details of early development.
Abstract: The growth of the rhabdosome from the initial prosicula is described for two species of Monograptus . Sections of the metasicula have shown the nature of the “Stillstandsgurtel” first described by Kraft, and in both species evidence about the structure of the interthecal septum is given. It appears that there are two forms of Monograptus dubius which have the same external appearance but differ in the details of early development.
TL;DR: Evidence about the structure of the interthecal septum is brought forward and so stages in the formation of one thecal segment can be defined.
TL;DR: A structural study of the Hecla Hook formation in the area of Forlandsundet of Vestspitsbergen revealed the presence of two B-axes as mentioned in this paper.
Abstract: "A structural study of rocks of the Hecla Hook formation in the area of Forlandsundet of Vestspitsbergen reveals the presence of two B-axes. The earlier (B 1 ) trends roughly east-west and affects only the Hecla Hook formation; the later axis (B 2 ) trends roughly north-south, and affects also rocks of Carboniferous age. It is suggested that B 1 is the main 9Caledonian9 axis in this area, and that B 2 and the roughly north-south 9grain9 of the rocks concerned are lower Tertiary phenomena."
TL;DR: In this paper, seven species of ammonites are described from the Lungma (Langma) limestone of Mekyigunru, eight miles south of Kampadzong, Tibet.
Abstract: Seven species of ammonites are described from the Lungma (Langma) limestone of Mekyigunru, eight miles south of Kampadzong, Tibet. The genera Sonninia, Witchella, Dorsetensia, and Emileia are represented; two species are new--Witchella tibetica and Dorsetensia? haydeni. The age is middle Bajocian (Jurassic), with only the Sowerbyi and Sauzei zones present, from which it is inferred that the formation here represents a condensed deposit.
TL;DR: In this paper, it was shown that at the maximum of Quaternary glaciation, small, thin glaciers developed in the island of St Kilda at certain favourable places, and no evidence that the Hebridean ice sheet reached the island and no signs of raised beaches which would indicate recent emergence.
Abstract: "Moraines which in one case at least contain striated boulders, show that, at the maximum of Quaternary glaciation, small, thin glaciers developed in the island of St. Kilda at certain favourable places. There is no evidence that the Hebridean ice sheet reached the island and no signs of raised beaches which would indicate recent emergence."
TL;DR: New generic names are given to seven well-known ammonites, previously figured, in order that they may be included in the new Treatise on Invertebrate Paleontology.
Abstract: Well-defined genera of ammonites from the Toarcian, Bathonian, Oxfordian, Kimeridgian, and Tithonian are diagnosed and named.
TL;DR: A brief report on the Garbh Eilean-Eilean an Tighe sill in the Shiant isles off the west coast of Scotland is given in this article, noting that the junction of picrite with overlying picrodolerite is abrupt rather than transitional and that the picrite layer does not maintain an even level in the sill.
Abstract: A brief report on the Garbh Eilean-Eilean an Tighe sill in the Shiant isles off the west coast of Scotland, noting that the junction of picrite with overlying picrodolerite is very abrupt rather than transitional and that the picrite layer does not maintain an even level in the sill.
TL;DR: In this paper, it is considered that some fossils, e.g. Orbulina and Miogypsina, are good indicators that beds containing them are of post-Oligocene age, and that the ages of some beds in certain parts of the world require reconsideration.
Abstract: "It is considered that some fossils, e.g. Orbulina and Miogypsina, are good indicators that beds containing them are of post-Oligocene age, and that the ages of some beds in certain parts of the world require reconsideration; mention is made of successions in Morocco, Venezuela, and Peru. It is recommended that the use of the term 9Aquitanian9 be restricted to beds of basal Miocene age."
TL;DR: The Kinlochleven Inversion was established by current bedding and is unquestioned as mentioned in this paper, and the Eilde Quartzite here floats on Eilde Schist, younger than itself.
Abstract: As is well known the northern face of Garbh Bheinn, which rises from Loch Leven east of Caolasnacon farm, is occupied by a “very obvious asymmetric downfold” of inversion Eilde Quartzite (Hardie, 1952, p. 273; Bailey, 1934, p. 485). The inversion is established by current bedding and is unquestioned. The Eilde Quartzite here floats on Eilde Schist, younger than itself. The occurrence marks the western end of the Kinlochleven Inversion, one of the most remarkable geological structures known to science.
TL;DR: A preliminary examination of Moine rocks containing rolled garnets from three widely spaced localities in the north-west Highlands [Scotland] indicates that the lineation in all cases is parallel to b. This is in accord with Phillips' theory that the metamorphism of the Moine schists was due to movement in a north-easterly or south-westerly direction as discussed by the authors.
Abstract: "A preliminary examination of Moine rocks containing rolled garnets from three widely spaced localities in the north-west Highlands [Scotland] indicates that the lineation in all cases is parallel to b. This is in accord with Phillips' theory that the metamorphism of the Moine schists was due to movement in a north-easterly or south-westerly direction. A Caledonian age for the metamorphism of the Moines therefore appears to be unlikely."
TL;DR: In this article, the authors examined morphological features in the test of zonal assemblages of Echinocorys scutata Leske from the Upper Chalk of Berkshire, Buckinghamshire, Hampshire, and Wiltshire.
Abstract: Selected morphological features in the test of zonal assemblages of Echinocorys scutata Leske from the Upper Chalk of Berkshire, Buckinghamshire, Hampshire, and Wiltshire, have been examined and measured. The results suggest that the changes observed in these characters at certain levels in the Chalk would have made Echinocorys more suited to a burrowing or partially burrowing habit. These adaptations are associated with lithological indications of shallow water deposition. It is suggested that the shallowing of the sea was the environmental stimulus behind the adaptations towards a burrowing mode of life.
TL;DR: The diorites and Sron a' Chro' granite of the Glen Tilt complex enclose hornblende-schist xenoliths derived from the Dalradian epidiorites of the country rock.
Abstract: The diorites and Sron a' Chro' granite of the Glen Tilt complex enclose hornblende-schist xenoliths derived from the Dalradian epidiorites of the country rock. Small hornblendite xeoliths are found in the complex but are restricted to the diorite outcrop. Porphyroblastic hornblende is developed within the schist xenoliths and reaction zones rich in hornblende are formed around the xenoliths. The mineralogical and textural characteristics of these reaction products suggest that the typical two-hornblende generation appinites of the complex represent modified hornblende schist. A similar origin for the quartz-orthoclase-appinite of the complex is rejected and their development from hornblendite is indicated.
TL;DR: In this paper, a re-examination of nephelinite from Little Mount Cameroon (Etinde) has shown that the feldspathoid mineral is actually nepheline and not orthorhombic KAlSiO 4 as has been occasionally suggested.
Abstract: Re-examination of nephelinite from Little Mount Cameroon (Etinde) has shown that the feldspathoid mineral is actually nepheline and not orthorhombic KAlSiO 4 as has been occasionally suggested. Chemical data are given, and a comparison is made with nepheline contained in mariupolite from the Vaal river region, Transvaal, South Africa. Also included is an analysis of nepheline syenite pegmatite from Cul Mor, Rossshire, Scotland, now available.
TL;DR: In this paper, the velocity of wind/porosity of deposit relationship has been investigated and it is shown that it is a more complicated function than was previously believed, and experiments on Ham river and Leighton Buzzard sands are discussed with reference to the influence of shape and specific gravity of sand grains on the velocity and porosity relationship.
Abstract: Continued investigation of the velocity of wind/porosity of deposit relationship since the first results were published in 1950 has shown that it is a more complicated function than was previously believed. Experiments on Ham river and Leighton Buzzard sands are discussed with reference to the influence of shape and specific gravity of sand grains on the velocity/porosity relationship.
TL;DR: In this article, small quartzite xenoliths scattered throughout the granodiorite are mantled by broad mafic coronas, the inner part of which is composed largely of augite and the outer part mainly of hornblende.
Abstract: "Small quartzite xenoliths scattered throughout the granodiorite are mantled by broad mafic coronas, the inner part of which is composed largely of augite and the outer part mainly of hornblende. The formation of the coronas is examined and some general features of magmatic reaction with quartzite inclusions are discussed."
TL;DR: Daviesiella destinezi appears to be restricted to the C 2 S 1 subzone of the lower Carboniferous of northwest Ireland and is therefore a useful index fossil as discussed by the authors.
Abstract: Daviesiella destinezi appears to be restricted to the C 2 S 1 subzone of the lower Carboniferous of northwest Ireland and is therefore a useful index fossil. A detailed description of good specimens from Fermanagh county is given. The relation of some of the morphological features to the environment is considered.
TL;DR: In this paper, the existence of the P1b, P1c, P2, E1a zones and possibly the E1c zone was established from the lowermost 450 feet of the Yoredale Shale.
Abstract: Of the three main lithological units on Cuilcagh, namely, Millstone Grit, Yoredale Sandstone, and Yoredale Shale, particular attention is paid to the latter which attains a thickness of 700 feet. Numerous goniatites were collected from the lowermost 450 feet of it and these establish the existence of the P1b, P1c, P2, E1a zones and possibly the E1c zone also. Higher beds are very poorly fossiliferous and their age is uncertain. Brief comparisons are also made with Yoredale Beds in England and in other parts of Ireland.